Design and Synthesis of Functionalized Styrene-Butadiene Copolymers by Means of Living Anionic Polymerization

Styrene-butadiene copolymers (SBR) end-functionalized with dimethylamino groups at the initiating and terminating chain-ends were successfully synthesized by a one-step methodology based on living anionic polymerization using 1-(4-dimethylaminophenyl)-1-phenylethylene. The expected structures of the resulting copolymers were confirmed by ¹H-NMR, SEC, and SLS analyses, titration, and model reactions. Furthermore, the possible synthesis of tri-functionalized styrene-butadiene copolymer with dimethylamino groups in a chain by extending the methodology is described.     

Synthesis of well-defined multifunctionalized polystyrenes with benzyl bromide moieties by a novel iterative divergent approach

Well-defined chain-end-functionalized polystyrenes with two, four, eight, sixteen, and thirty-two benzyl bromide moieties were synthesized by the methodology based on a novel iterative divergent approach. In this methodology, the entire iterative synthetic sequence involves only two sets of the reactions: a coupling reaction of the terminal benzyl bromide moieties with the functionalized anion prepared from 1,1-bis(3-tert-butyldimethylsilyloxymethylphenyl)ethylene and sec-BuLi and a transformation reaction of the introduced tert-butyldimethylsilyloxymethyl groups into bromomethyl functions by treatment with LiBr-(CH₃)₃SiCl. The iteration started with chain-end-functionalized polystyrene with one benzyl bromide moiety and could be repeated five times. All iterations proceeded quantitatively to afford chain-end-functionalized polystyrenes with a definite number of benzyl bromide moieties up to thirty-two.     

Total Synthesis of Dictyodendrins A–F by the Gold-Catalyzed Cascade Cyclization of Conjugated Diyne with Pyrrole

The total synthesis of dictyodendrins A–F was achieved by using the gold(I)-catalyzed annulation of a conjugated diyne with N-Boc-pyrrole for direct construction of the pyrrolo[2,3-c]carbazole scaffold. Late-stage functionalization of the resulting pyrrolo[2,3-c]carbazole to introduce various substituents provided divergent access to dictyodendrins. Some dictyodendrin analogues exhibited inhibitory activities toward CDK2/CycA2 and GSK3.     

Probing the Majorana nature of TeV-scale radiative seesaw models at collider experiments

A general feature of TeV-scale radiative seesaw models, in which tiny neutrino masses are generated via loop corrections, is an extended scalar (Higgs) sector. Another feature is the Majorana nature; e.g., introducing right-handed neutrinos with TeV-scale Majorana masses under the discrete symmetry, or otherwise introducing some lepton number violating interactions in the scalar sector. We study phenomenological aspects of these models at collider experiments. We find that, while properties of the extended Higgs sector of these models can be explored to some extent, the Majorana nature of the models can also be tested directly at the International Linear Collider via the electron–positron and electron–electron collision experiments.     

Scanning laser microscope for imaging nanostructured superconductors

The nanofabrication of superconductors yields various interesting features in superconducting properties. A variety of different imaging techniques have been developed for probing the local superconducting profiles. A scanning pulsed laser microscope has been developed by the combination of the XYZ piezo-driven stages and an optical fiber with an aspheric focusing lens. The scanning laser microscope is used to understand the position-dependent properties of a superconducting MgB₂ stripline of length 100 μm and width of 3 μm under constant bias current. Our results show that the superconducting stripline can clearly be seen in the contour image of the scanning laser microscope on the signal voltage. It is suggested from the observed image that the inhomogeneity is relevant in specifying the operating conditions such as detection efficiency of the sensor.     

Electronic-phase transition of the Hartree–Fock solution of the infinite one-dimensional system: Structural change in an arbitrarily doped polyacetylene chain

The concept of the electronic-phase transition of the Hartree–Fock solution has been applied to an arbitrarily doped polyacetylene (PA) chain to examine the structural change of the polymer skeletons under such doping regimes. It has been found that the n-doped PA chain tends to suppress the generation of the charge-density wave (CDW ) phase, whereas the p-doped PA favors the CDW phase leading to the charged-soliton shape. © 1993 John Wiley & Sons, Inc.     

High performance of thin nano-crystalline ZrN diffusion barriers in Cu/Si contact systems

A thermally stable thin diffusion barrier in Cu/Si contacts was developed using a thin nano-crystalline ZrN film. The Cu/ZrN/Si contact system using a reactively sputtered ZrN barrier with 20 nm in thickness consisting of several to 10 nm grains tolerated annealing at 600 °C for 1 h without any Cu penetration through the barrier. This was interpreted that the scarce structural change in the prepared nano-crystalline ZrN film due to annealing was favorite for the thermal stability of thin barrier application.     

Determination of indium by graphite furnace atomic absorption spectrometry after coprecipitation with chitosan.

A sensitive and simple method for the determination of trace amounts of indium in water samples by graphite furnace atomic absorption spectrometry (GFAAS) after coprecipitation with chitosan was investigated. Indium was quantitatively preconcentrated from water samples by coprecipitation with chitosan at pH 7.0-9.0. The coprecipitant was easily dissolved with acetic acid, and indium in the resulting solution was determined by GFAAS. The addition of lanthanum as a chemical modifier was more effective for the atomic absorbance of indium. The detection limit (S/N > or = 3) for indium was 0.04 microg dm(-3), and the relative standard deviations (n = 5) were 3.5-4.5% at 1.0 microg/100 cm3. The results obtained in this study indicate that the proposed method can be successfully applied to the determination of trace indium in water samples.     

Surface-Carboxylated Nanocellulose-Based Bioadaptive Scaffolds for Cell Culture

Cellulose - The extracellular matrix (ECM) is critical to cell attachment, proliferation, and differentiation; therefore, development of bioadaptive ECM-mimetic cell culture scaffolds is an active...